July 2008 - AMSAT-BB - mailman.amsat.org

Help for Landwehr El. 70 cm preamp GaAsfet
by gfronconi＠alice.it 03 Jul '08

03 Jul '08

Hi all, in 1989/90 I bought a Landwehr Electronics preamp for 70 cm band and all was OK till now.A few weeks ago,for some reason,( may be an electrical shock during a storm ) the GaAsfet decided to die. Unfortunately it is impossible to read the name of the GaAsfet to be replaced and on Landwehr technical sheet for 70 cm preamp,the GaAsfet is listed as IC with no particular specification. No useful answer to my e-mails about the type of GaAsfet used from Landwehr El. in Germany. So,I hope someone can help me to find the name of that GaAsfet, I would appreciate. Thanks. Gianfranco Ronconi IK4GMI

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Comment on ASMO (American Student Moon Orbiter)
by James Whitfield 03 Jul '08

03 Jul '08

So that you will know "where I am coming from", let me say that I am not an active satellite user. I am a semi-retired aerospace engineer, in that I work part time on a NASA project - the modification of a 747 to carry a sub-millimeter and infrared telescope into the stratosphere. I had my hands into amateur radio, literally, before Sputnik, though I did not get my license until years later. I cannot remember when I was not interested in space exploration. My first engineering job was testing rocket motors and associated prototype hardware for the first and second stages of what evolved into the Peacekeeper missile. And for a brief time I tried to be an educator. My opinion is that ASMO is a result of the stark realization by NASA, whether from within or forced on it by national leadership, that the supply of skills to build and operate spacecraft is rapidly drying up at a time when national goals are to expand our reach into space by returning to the Moon and perhaps sending people to Mars. Within the ASMO website is the statement that twenty-five persent of NASA employees are eligible to retire in less than five years. The problem is similar for the companies that NASA depends on to develop and operate its various systems. Indeed the entire aerospace industry, while facing major difficulties due to the current fuel prices, will have severe personnel shortages for decades. Even when engineers and scientists can be hired, they still face the problem of learning what it is that they are hired to do. A problem particularly acute for NASA since they tend to be doing things that have never been done before. ASMO is an attempt to find solutions to both of these areas of concern. You may ask how this relates to AMSAT. First, for those of you that work with students, you might get the opportunity, assuming of course that ASMO gets off the ground, to encourage students to seek a university program that will allow them to build and operate satellites. Presumably, you will have converted them to AMSAT members along their path. At the very least they should recognize that the amateur radio community is a friendly ally. And if you are an AMSAT member preparing to go to college, and have some interest in a program like ASMO, then by all means go for it. ( And keep an open mind for projects that can attract more students to follow you. ) For those of you not already working with students, here is your chance to influence not only the future scientists and engineers that will be building future spacecraft, but it is an excellent opportunity to connect with, and begin to influence, the universities that will be training them. Not so long ago, I read here some comments ( Dare I say grousing? ) about university satellite projects using amateur frequencies and assets, but then giving nothing back to the amateur radio community for their service. Meet with them. Propose activities to work together. Demonstrate to them that working with you is in their own self interest. Show your stuff. Of course you won't get all of them interested in your hobby, but you might get a lot more than you have now. Suppose you took the time to submit some ideas to NASA about the kind of things that a student project should include. Remember, the intent is to allow students to learn about building and operating an entire space probe. Point out that the students should include communications ( not just depend on the existing NASA communication system ) as part of the system. There is room for thought about communications experiements - perhaps a radar sensor array could be pointed at the Earth when not being used to scan the Moon. Students could learn a lot more about communications, if say the "radar" was commanded to listen first, then transmit back something that it "heard". Think outside the box. Don't limit yourself to the mindset that a radar sends an unmodulated burst and listens to the echo, which is processed for information. The same "box" can listen, process, then transmit. Do the math. Suggest alternatives. Point out that if the probe can be heard on the Earth with amateur radio equipment, then millions of people can listen. It certainly worked for Sputnik. Be realistic. If you suggest a system that you can kerchunk with an HT in your back yard, I don't think it will get much favor. But then again, the intent is to give student experience to a real probe that will gather significant data to be used for future lunar exploration. This program is not about what you want, but about what is a good experience for the students. If you think about it, you might find that "good for the students" might benefit you as well. You are the people who have shown interest in building and operating spacecraft. You are the kind of people that NASA wants to hear from. James Whitfield n5gui

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Re: Commercial Mode L Antenna sources
by Wayne Estes 03 Jul '08

03 Jul '08

I'm surprised how few people have mentioned parabolic dishes during this discussion about commercial Mode L antennas. L-band uplinks are mostly used in combination with a S-band downlink. Most people build L/S equipment with HEO satellites in mind. A single yagi or helix doesn't usually provide sufficient gain for L/S band use with a HEO satellite. You need the gain of a dish for satisfactory S-band reception of a HEO satellite. So one practical solution is an oversized dish with a L/S dual-band feed (helix or patch). A 4-foot dish was proven to work well for this on AO40. In my opinion a single 4-foot dish is more practical than, for example, cobbling together multiple yagi/helix antennas for S-band downlink and multiple yagi/helix antennas for L-band uplink. My 4-foot dish and dual-band patch feed were purchased commercially from Teksharp (Rick Fletcher KG6IAL). http://www.plumdragon.com/teksharp/hr_AO-40_products.htm The dual-band patch feed is sold fully assembled and tested, but the dish was a kit. I had to locally purchase 1/4 inch hardware cloth, cut it into 8 "petals", and use 200 zip ties to attach the petals to the frame of the dish. A mesh dish has somewhat less wind loading than a solid dish. That's important because a solid 4-foot dish has a maximum wind load of more than 12 square feet, exceeding the wind load rating of my G-5500 rotor. A picture of my satellite antennas can be seen here: http://s238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/ Wayne Estes W9AE Oakland, Oregon, USA, CN83ik

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Re: NASA's American Student Moon Orbiter...
by w7lrd＠comcast.net 03 Jul '08

03 Jul '08

How would my 12 foot paraclips work for this exercise? 73 Bob W7LRD -- "if this were easy, everyone would be doing it" -------------- Original message -------------- From: "Andrew Glasbrenner" <glasbrenner(a)mindspring.com> > The moon is roughly 360,000 to 400,000 km away. By comparison, AO-40 had a > apogee of about 60,000km. At 2.4Ghz, that's about 16db difference each way. > Put AO-40 at the moon, and if I'm doing this right, you'd need about 32 > times the ground station antenna both coming and going to get with a few db. > I'm gonna need a bigger rotor for sure! I'm sure smarter folks will check my > math.... > > 73, Drew KO4MA > > ----- Original Message ----- > From: "Joe" > To: "Andrew Glasbrenner" > Cc: "Trevor" ; "AMSAT BB" > Sent: Wednesday, July 02, 2008 6:05 PM > Subject: Re: [amsat-bb] Re: NASA's American Student Moon Orbiter... > > > > what would a sample average link budget be? > > > > Andrew Glasbrenner wrote: > > > >>As far as I can recall we are pursuing both Eagle and the P4 opportunity > >>equally, concentrating on common elements until the details are ironed > >>out. Neither has been identified as a primary or secondary objective. > >> > >>I agree a package on a lunar orbiter would be neat, but also that it is > >>not the best use of what volunteers we have. We need more folks to step up > >>to do things, AND we need to make better use of them when they do. > >> > >>73, Drew KO4MA > >> > >>----- Original Message ----- > >>From: "Trevor" > >>To: "AMSAT BB" > >>Sent: Wednesday, July 02, 2008 4:53 PM > >>Subject: [amsat-bb] Re: NASA's American Student Moon Orbiter... > >> > >> > >> > >>>--- On Wed, 2/7/08, Dave hartzell wrote: > >>> > >>>>http://www.spaceref.com/news/viewpr.html?pid=25839 > >>>>http://asmo.arc.nasa.gov/ > >>>> > >>>>Wouldn't it be fun to have a transponder on this! ;-) > >>>> > >>>Fun yes, but dare I say it, a waste of precious Volunteer resources. > >>> > >>>All lunar orbits are inherently unstable and will impact after a couple > >>>of years. The link budget requirements would not attract a mass user > >>>base. > >>> > >>>I suspect the number of Technically Capable volunteers is already being > >>>thinly stretched in trying to provide both the primary objective Phase-IV > >>>Lite (funded by Federal Government dollars) and the secondary objective > >>>the Eagle HEO. > >>> > >>>73 Trevor M5AKA > >>> > >>> > >>> > >>> __________________________________________________________ > >>>Not happy with your email address?. > >>>Get the one you really want - millions of new email addresses available > >>>now at Yahoo! http://uk.docs.yahoo.com/ymail/new.html > >>> > >>>_______________________________________________ > >>>Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > >>>Not an AMSAT-NA member? Join now to support the amateur satellite > >>>program! > >>>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > >> > >>_______________________________________________ > >>Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > >>Not an AMSAT-NA member? Join now to support the amateur satellite program! > >>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > >> > >> > >> > >> > > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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Re: Commercial Mode L Antenna sources
by w7lrd＠comcast.net 02 Jul '08

02 Jul '08

Hi Wayne and all I agree a four footer would be good for L/S. I used a four foot primestar for AO-40 (sobsob) on S band. I now have as yet untried dual feed for L/S for the same dish. I'm waiting fo the energy to connect everything up and give it try. I need another downconverter and a bird 43 L band slug, for tweeking. The feed is two concentric helix feeds on the same form for L/S. Should I not get desense to to proximity of the feeds it will be my future L/S antenna. Yes the primestar is solid and heavy, being off center feed it will lend itself to helix as opposed to a patch feed. I have heard the 3731AA downconverters from K5GNA have a good front end. I also have a UEK 3000 downconverter. Which will be be better, I don't know as yet. If anyone has tread here before I would appreciate your input. 73 Bob W7LRD Seattle -- "if this were easy, everyone would be doing it" -------------- Original message -------------- From: Wayne Estes <w9ae(a)charter.net> > I'm surprised how few people have mentioned parabolic dishes during this > discussion about commercial Mode L antennas. L-band uplinks are mostly > used in combination with a S-band downlink. Most people build L/S > equipment with HEO satellites in mind. A single yagi or helix doesn't > usually provide sufficient gain for L/S band use with a HEO satellite. > You need the gain of a dish for satisfactory S-band reception of a HEO > satellite. So one practical solution is an oversized dish with a L/S > dual-band feed (helix or patch). A 4-foot dish was proven to work well > for this on AO40. In my opinion a single 4-foot dish is more practical > than, for example, cobbling together multiple yagi/helix antennas for > S-band downlink and multiple yagi/helix antennas for L-band uplink. > > My 4-foot dish and dual-band patch feed were purchased commercially from > Teksharp (Rick Fletcher KG6IAL). > http://www.plumdragon.com/teksharp/hr_AO-40_products.htm > The dual-band patch feed is sold fully assembled and tested, but the > dish was a kit. I had to locally purchase 1/4 inch hardware cloth, cut > it into 8 "petals", and use 200 zip ties to attach the petals to the > frame of the dish. A mesh dish has somewhat less wind loading than a > solid dish. That's important because a solid 4-foot dish has a maximum > wind load of more than 12 square feet, exceeding the wind load rating of > my G-5500 rotor. A picture of my satellite antennas can be seen here: > http://s238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/ > > Wayne Estes W9AE > Oakland, Oregon, USA, CN83ik > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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AO-51 Field Day mode
by Andrew Glasbrenner 02 Jul '08

02 Jul '08

In reading through the e-mails to -bb, it seems L/U was well received among the membership on Field Day? I'd be interested in feedback about Field Day for consideration of next year's mode. Feel free to cc the -bb, as I'm sure it's of interest to many. 73, Drew KO4MA PS Congratulations to the handful of stations who were listening to AO-16 Saturday afternoon and Sunday morning. I manually turned the satellite on several times on each of three passes, and several stations managed QSOs in the brief periods the old bird stayed on. Myself and the other command station will continue to try to restart the repeater when available, and maybe as temperatures change it will stay on a little longer, but no promises can be made.

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Office Closed
by Martha 02 Jul '08

02 Jul '08

The AMSAT office will be closed on Friday, July 4th and Monday, July 7th. -- 73- Martha

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Logbook Software Suggestions
by John Henderson N4NAB 02 Jul '08

02 Jul '08

Would appreciate a suggestion for logbook sw that includes satellite operations. I have looked at a number of them but you have to " force feed" the sat info. Thanks, John John Henderson N4NAB 212 Bayside Drive Cape Carteret, NC 28584

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Commercial Mode L Antenna sources
by Ronald Nutter 02 Jul '08

02 Jul '08

I am thinking about putting in a 1.2 Ghz module in m IC910H. That has me looking at Mode L antennas. Until my browser blew up a few weeks ago, I had severa links to antenna candidates but have lost those now. Would appreciate any links to antennas that are usable with AO-51 and maybe the phase 3 birds when they launch. Thanks, Ron KA4KYI

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Re: Best type of coax to use ... in ... AMSAT-BB Digest, Vol 3, Issue 326
by joe cassano aka jmario 02 Jul '08

02 Jul '08

Installing a classic clamp type N connector like the Amphenol 82-202 (UG-21D/U) on flexible coax with a real copper center conductor (RG-8,RG-213) is both easier and has a much higher probability of success than installing the common PL-259. You only have to make one easily accessible solder connection. Take a look at http://www.amphenolrf.com/products/assemblyInstructions/280.pdf to see what is involved in attaching classic clamp style N connector. You also might want to read the reviews listed here: http://www.eham.net/reviews/products/7 before you make any purchase decisions. Regards, JoeC - K3FMA > ------------------------------ > > Message: 12 > Date: Mon, 30 Jun 2008 19:49:00 -0500 > From: Ronald Nutter <rnutter(a)networkref.com> > Subject: [amsat-bb] Best type of coax to use between preamps and > antennas > To: amsat-bb(a)amsat.org > Message-ID: <48697EFC.5010100(a)networkref.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > After problems I had on Field Day in trying to operate the satellites, I > am looking to upgrade the coax I use between the preamps and the > antennas. I am using 9913FX from the IC-910H and the preamps. I had > been using RG Mini 8/U for the connection between the preamps and > antennas. Should I also use 9913FX between the preamps and the > antennas? The run between the radio and the preamp is 50 ft. The run > from the preamp to the antennas is about 10 - 15 ft depending on where I > set the antennas up. I am concerned about how flexible the 9913FX would > be in terms of the antennas rotating back and forth. I was planning on > ordering the cables pre-made from CableXperts since working with N > connectors isnt my strong point and dont want to worry about my > soldering and having a good connection on both ends of the cable. > > Any suggestions appreciated. > > Thanks, > Ron > KA4KYI > >

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